Fig. 8. Effects of Ldb1 or XRnf12 overexpression on organizer gene expression. Embryos injected dorsally with the mRNAs indicated were scored for expression of various marker genes in the organizer as assayed by whole-mount in situ hybridization. Genes categorized in group 1 (A-E, gsc, chd, Xotx2, XPAPC and cer) are downregulated by overexpression of either Ldb1 or XRnf12, whereas genes categorized in group 2 (F,G, XFKH1 and Xnot) are downregulated only by XRnf12, and those in group 3 (H,I, dkk1 and Mix.1) are downregulated only by Ldb1. Xbra (J) is only slightly affected by Ldb1 overexpression. Numbers indicate the frequency of the phenotype observed: numbers in red indicates downregulation, whereas numbers in black or white indicates normal expression. Note that downregulation of gene expression by either Ldb1 or XRnf12 overexpression was restored upon co-expression of both, and that the rescuing effect of XRnf12 co-expression was RING-dependent (except for dkk1, see Discussion). nß-gal mRNA was coinjected as a lineage tracer, stained in red. Amounts of mRNAs (ng/embryo): nß-gal, 0.06; ß-globin, 4.0; Ldb1, 4.0; XRnf12, 2.0 or 4.0; XRnf12 constructs coinjected with Ldb1, 1.0 or 2.0.

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